Measuring Circuit Loads at DVinfo.net

Eric Lagerlof · February 8th, 2006, 11:12 PM

Is there any slick way using a multi-meter or other device to measure the current load on a circuit? i.e. Making sure you can detect the 400 watts of a computer you didn't realize was on somewhere else in the house before you add your 1,800 watt lighting kit to a 20 amp circuit. Also, is there a cheap "Fox and Hound" 'circuit finder' that someone could recommend?

Walter Graff · February 8th, 2006, 11:16 PM

Quote:

Originally Posted by Eric Lagerlof

Is there any slick way using a multi-meter or other device to measure the current load on a circuit? i.e. Making sure you can detect the 400 watts of a computer you didn't realize was on somewhere else in the house before you add your 1,800 watt lighting kit to a 20 amp circuit. Also, is there a cheap "Fox and Hound" 'circuit finder' that someone could recommend?

There is but it would require a meter that clamps around one hot cable alone and the only way to do that is inside an electrical box so I would say no, because most folks d o not know how to safely open a box, let alone play inside of it.

Matt Irwin · February 9th, 2006, 10:12 PM

Look for a device called an Amp Probe.

Walter Graff · February 11th, 2006, 09:51 AM

Amp probes are good for general references but have a lousy bar graph that is in 5 amp blocks and isn't as accurate as a real amp meter.

Eric Lagerlof · February 13th, 2006, 12:23 PM

Sorry to get back to you so late...unexpected shoot for CSPAN. Thanks for the tips. Matt, I saw an amp probe for about $40.00, the K1-KwikE, I think. It has the bar graph Walter was referring to. Is this what you meant? Walter, even if it's 5 amps off, a rough idea would really help. (I always try and leave about 3 amps headroom on a circuit if I can.) This comes out of a concern for situations like run and gun office shoots, where the house engineer really doesn't know how many computers/cubicles are on that floor circuit you want to use. I was at Barnes & Noble yesterday and the store manager couldn't tell us about whether the plugs we were using for the video lights were on a different system than the outlet for video village and was paranoid about cord runs through the store to use say, the bathroom outlet that would most likely be on a seperate circuit. So would the KI do at least that much reliably?

Walter Graff · February 13th, 2006, 02:50 PM

It's probably a start and would help get you in the ballpark but it will not guarantee you will not blow circuits. But here is your problem. It is meant to be in contact with the sleeve of a hot wire, not stuck in or near an outlet so I do not know how reliable or if it would work at all doing such a thing.

Eric Lagerlof · February 14th, 2006, 03:37 PM

According to Michael at "Test Equipment Depot", you use a clamp meter and a AC Line Splitter. The splitter plugs in to the wall and with a reasonably inexpensive calmp meter attatched to the splitter (instead of bare wire), your set t measure circuit loads. Together for around $100, I believe.

February 8th, 2006, 11:12 PM	#1
Eric Lagerlof Major Player Join Date: Mar 2004 Location: Pacifica, CA Posts: 348	Measuring Circuit Loads Is there any slick way using a multi-meter or other device to measure the current load on a circuit? i.e. Making sure you can detect the 400 watts of a computer you didn't realize was on somewhere else in the house before you add your 1,800 watt lighting kit to a 20 amp circuit. Also, is there a cheap "Fox and Hound" 'circuit finder' that someone could recommend?

February 9th, 2006, 10:12 PM	#3
Matt Irwin Major Player Join Date: Jul 2004 Location: Los Angeles, CA Posts: 327	Look for a device called an Amp Probe. __________________ Matt Irwin DP / matt.irwincine.com

February 11th, 2006, 09:51 AM	#4
Walter Graff Hellgate Pictures, Inc. Join Date: Nov 2002 Location: New York, NY Posts: 124	Amp probes are good for general references but have a lousy bar graph that is in 5 amp blocks and isn't as accurate as a real amp meter.

February 13th, 2006, 12:23 PM	#5
Eric Lagerlof Major Player Join Date: Mar 2004 Location: Pacifica, CA Posts: 348	Sorry to get back to you so late...unexpected shoot for CSPAN. Thanks for the tips. Matt, I saw an amp probe for about $40.00, the K1-KwikE, I think. It has the bar graph Walter was referring to. Is this what you meant? Walter, even if it's 5 amps off, a rough idea would really help. (I always try and leave about 3 amps headroom on a circuit if I can.) This comes out of a concern for situations like run and gun office shoots, where the house engineer really doesn't know how many computers/cubicles are on that floor circuit you want to use. I was at Barnes & Noble yesterday and the store manager couldn't tell us about whether the plugs we were using for the video lights were on a different system than the outlet for video village and was paranoid about cord runs through the store to use say, the bathroom outlet that would most likely be on a seperate circuit. So would the KI do at least that much reliably?

February 13th, 2006, 02:50 PM	#6
Walter Graff Hellgate Pictures, Inc. Join Date: Nov 2002 Location: New York, NY Posts: 124	It's probably a start and would help get you in the ballpark but it will not guarantee you will not blow circuits. But here is your problem. It is meant to be in contact with the sleeve of a hot wire, not stuck in or near an outlet so I do not know how reliable or if it would work at all doing such a thing.

February 14th, 2006, 03:37 PM	#7
Eric Lagerlof Major Player Join Date: Mar 2004 Location: Pacifica, CA Posts: 348	According to Michael at "Test Equipment Depot", you use a clamp meter and a AC Line Splitter. The splitter plugs in to the wall and with a reasonably inexpensive calmp meter attatched to the splitter (instead of bare wire), your set t measure circuit loads. Together for around $100, I believe.